The carbonation apparatus, generally referred to as a carbonator, used in conjunction with post-mix carbonated beverage dispensers and/or vending machines, for example, is well-known. FIG. 1 shows a typical prior art carbonator 10. It includes means for supplying both fresh uncarbonated water 16 and carbonating gas, such as CO.sub.2, 26 at a regulated pressure to a carbonator tank 12 where the two are mixed to form carbonated water 30. It also includes a conduit for transporting carbonated water 30 from carbonator tank 12 to a post-mix dispensing nozzle 42 of a post-mix tower and dispenser assembly 40, where the carbonated water 30 is mixed in suitable proportions with a quantity of flavor concentrate or syrup 34 from a supply source 32 to produce the composite carbonated drink.
Carbonator 10 also normally includes some type of water pump 18 to supply and replenish uncarbonated water 16 from water supply 14 at an elevated pressure to the carbonator tank 12 which also receives CO.sub.2 at elevated pressures from a source 24. Both mechanical and electrical pump configurations have been utilized. The pump 18 (and motor 20, in case of electrical configurations) is generally controlled by means of a level control 28 which senses the amount of carbonated water in the carbonator tank 12. Thus, when a volume of carbonated water 30 is dispensed from the carbonator tank 12, it is replaced by a fresh volume of pressurized non-carbonated water 22.
With the increased popularity of non-carbonated beverages such as tea, orange drink or lemon-lime, there is a greater need for post-mix tower and beverage dispenser assemblies that are equipped to provide both carbonated and non-carbonated beverages. Consequently, the prior art apparatus of FIG. 1 includes a conduit for transporting non-carbonated water 16 (which is generally at a low pressure) from water supply 14 to post-mix non-carbonated beverage dispensing nozzle 49, where non-carbonated water 16 is mixed with a suitable quantity of flavor concentrate or syrup 46 from source 44 to make the desired non-carbonated beverage. The water supply 14 for making the non-carbonated beverage may be the same supply as that utilized in carbonator tank 12 for making carbonated water 30.
A critical aspect of the mixing of the beverage syrup or concentrate (34 or 46) on the one hand, and the carbonated water 30 or non-carbonated water 16 on the other, is that the resulting beverage must be properly proportioned or "ratioed." Depending on the desired end beverage, a precise ratio of water and syrup must be mixed in order that the ultimate taste of the end beverage not be compromised. For example, if too little water or too much syrup are mixed, the end beverage would be sweeter than it ought to be for consumption.
In the case of making a carbonated beverage, because the carbonator tank 12 holds the carbonated water at an elevated and uniform pressure that is nearly independent of any fluctuations in pressure of the water supply 14, the proper ratios in mixing of the carbonated water 30 and the syrup 34 are not significantly compromised by any pressure fluctuations in the water supply 14.
However, if the non-carbonated water 16 is drawn from a typical water source 14 (e.g., tap water), the ratio of non-carbonated water 16 to syrup 46 will be affected by the variations or fluctuations that typically occur in the pressure of such a water supply 14. These pressure fluctuations may have numerous causes, including the use of water in other parts of the premises from which water is drawn, such as water fountains, sinks, showers, toilets, etcetera.
As non-carbonated beverages have garnerned a greater share of the beverage market, there have been efforts to find a solution to the detrimental effects of water pressure fluctuations on the proper ratio of the non-carbonated water 16 and the syrup or concentrate 46. One such effort to minimize the effect of pressure fluctuations in the water supply 14 is depicted in FIG. 2. There, the carbonation and post-mix beverage dispensing system of FIG. 1 is modified to include a separate means for pressurizing the non-carbonated water 16 drawn from source 14 and storing it in a separate water booster tank 50 for making the non-carbonated drink. Tank 50 is usually made of cold-rolled steel and includes an internal plastic liner or special coating to prevent rusting and/or the emission of metallic or other undesirable tastes. Tank 50 incorporates a membrane 51 such as a thick rubber diaphragm or bladder that is locked in place, dividing tank 50 into two sides. Membrane 51 is installed before tank 50 is closed, after which tank 50 is fully welded and sealed. Therefore, if membrane 51 should fail, tank 50 is usually completely discarded since there is no way to effect replacement of membrane 51, other than by cutting tank 50 open and attempting to reweld and reseal it.
One side of tank 50 is generally pre-charged with air to 30 psi at the tank manufacturer's location, however, additional pressure can be added by the customer up to as high as 100 psi. There is generally a tire valve stem 55 on one end of tank 50 to introduce the air pressure, with the opposite end having an inlet for plain water 56 to be admitted and stored. To overcome the pressure on the opposite (air) side of membrane 51, a pump and motor must be utilized. Water 16 from supply 14 may, for example, be pumped to the desired elevated pressure by pump means such as motor 54 and pump 52, and then supplied to tank 50. As water 56 enters the water side of tank 50, membrane 51 expands into the air side of tank 50, raising the pressure therein. When the air pressure is increased to the desired amount, pressure switch 60 will stop motor 54 and pump 52. Non-carbonated water 58 at the desired elevated pressure can then be drawn from tank 50 on demand for mixing with syrup 46 from syrup supply 44. A properly mixed non-carbonated beverage is then available at a designated post-mix dispensing nozzle or faucet 49.
The apparatus of FIG. 2, however, suffers certain deficiencies. Even with the separate water booster tank 50, dispensing non-carbonated drinks can be problematic, because water boosters generally do not exceed 100 psi and normally operate between 60 and 80 psi, while soda water carbonators pressures normally run from 100 to 150 psi. Accordingly, the proportions or rates of syrup flow for carbonated versus non-carbonated drinks need to be set differently. Further, the float controls may need to be sized differently in the non-carbonated faucets than in the carbonated faucets, resulting in increased equipment costs, installation costs, because of the extra parts, special spouts, diffusers and faucets. Moreover, the pressures of the carbonated versus non-carbonated water supplies are independent of each other, introducing further difficulties in trying to maintain the proper mixing ratios of water to syrup.
Further complicating matters, because the majority of drinks sold through most beverage dispensers are carbonated, dispenser faucets are usually equipped with diffusers that create a pressure drop to slow the soda water down as it pours into the cup, thereby preventing foaming. But, because the non-carbonated water pressure is generally already lower than that of the carbonated water, the further reduction in pressure created by these diffusers can cause the non-carbonated water to flow too slowly and/or in insufficient quantity.
A further problem posed by the independent water booster is that some customers like beverages dispensed with reduced carbonation, such as 50%. To achieve this, they may try to blend plain water in a 1:1 ratio with soda water in the faucet. The pressure differential between the carbonated and non-carbonated water supplies, however, may determine the actual ratio of carbonated to non-carbonated water, preventing the desired blending.
Moreover, from the standpoint of cost and space requirements, providing separate means of pressurizing and storing non-carbonated water for preparation of non-carbonated beverages is unsatisfactory. As seen in FIG. 2, the modified post-mix tower and dispenser assembly requires two pressure vessels (or tanks) 12 and 50, possibly two pumps 18 and 52, two motors 20 and 54, a liquid level control 28 set for making carbonated beverages, and a pressure switch 60 set for making non-carbonated beverages. Aside from space requirements (which in the beverage dispenser and vending machine industry is an important concern), this solution entails nearly double the costs of manufacturing, installing and servicing.
In short, the pressurization and pumping equipment required for the non-carbonated water for making non-carbonated beverages in conventional post-mix beverage dispensers and/or vending machines results in a relatively large, bulky, heavy and costly system which is ill-suited for utilization in low-volume, cost-driven, limited space environments, and still may not produce reliable results. Accordingly, there exists a significant need for an apparatus that provides both carbonated and non-carbonated water at a regulated pressure for making well-blended and properly proportioned carbonated and non-carbonated beverages. There is also a need for an apparatus that achieves these objectives in a cost-effective and space-efficient manner by way of a combined carbonator and water booster tank that functions both as a water carbonator and as a pressurized non-carbonated water source. Additionally, there is a need for an apparatus that can be economically retrofitted to existing carbonation units, yet still provide the aforementioned regulated and balanced pressure between the carbonated water and non-carbonated water.